As is well known, the knee joint, although frequently considered a hinge joint, actually comprises two joints, lateral and medial, between the femur and tibia, and one arthrodial joint between the patella and femur. The primary movements of the knee comprise flexion, i.e. rearward rotational movement of the tibia relative the femur, and extension, i.e. forward rotational movement of the tibia relative the femur.
The flexion and extension movements of the knee joint are not simply pivotal movements about a fixed axis. During flexion, the axis around which movement takes place shifts backward, and during extension it shifts forward. This is different from a more typical hinge joint, such as an elbow, where the axis of rotation does not shift. As full extension is reached, the tibia is rotated inward or rearward and the joint in effect is disposed in a "locked" position with the ligaments taut. This gives the joint greater stability in the extended position. As flexion is initiated, the tibia initially lowers or moves downwardly with a small external rotation of the tibia which "unlocks" the joint and subsequently the tibia rotates or rolls about the joint to full flexion. Accordingly, the initial unlocking of the knee joint during flexion proceeds actual full rotation of the knee.
Due to the above complexity of knee movement, for a brace to more fully support the knee joint of the user and facilitate rehabilitation and/or prevent re-injury of an injured knee joint, the brace must more closely analogize the movement of the knee than a simple hinge mechanism. Additionally, with specific relation to athletic or sports applications, the requirement for such analogized movement becomes acute. Further, for such sports applications, a knee brace must be relatively lightweight to avoid over constriction which reduces success in the athletic endeavor yet possess sufficient structural strength to adequately support the knee joint during impact thereupon.
In recognizing the need for an effective sports knee brace, various knee braces have been introduced into the marketplace. Such contemporary knee braces, however, have generally failed to provide the precise simulation of knee joint movement, as described above or have comprised relatively heavy, bulky apparatus thereby detracting from the user's athletic endeavor. Further, such contemporary designs have typically failed to possess sufficient structural integrity to prevent re-injury of the knee joint as may be occasioned by impact to the knee joint during physical sport endeavors.
Additionally, most contemporary sports braces have further been deficient in that the vertical plane of the brace and other physical parameters of the brace have been at the time of manufacture and hence have proven unsuitable for individual users having different curvatures or conditions of the leg at the level of the knee. Such conditions are commonly attributable to an imbalance between the medial and lateral support of the knee. Lack of adequate lateral support of the knee may produce a bowlegged condition, i.e. outward curvature of the leg adjacent the level of the knee. A lack of medial support of the knee may produce a knock-kneed condition, characterized by an inward curvature of the leg at the level of the knee. As such, a brace designed for individuals having normal curvature of the leg at the level of the knee may therefore be uncomfortable or entirely unsuitable for bowlegged or knock-kneed individual users.
In recognizing these inherent deficiencies, the vast majority of contemporary knee braces have been manufactured on a prescription, i.e. one of a kind basis, to properly accommodate the differing physical parameters of the user. Such unique one of a kind fabrication significantly increases overall costs of the knee brace as well as increases delivery time of braces to the individual user. Consequently there exists a substantial need for a knee brace that may be manufactured to accommodate differing users and be subsequently adjusted at the time of placement or installation upon the user to properly support the knee of the user having various degrees of leg curvature and leg conditions at the level of the knee.